Constant velocity joints are commonly used in driveshaft assemblies of motor vehicles. One type of constant velocity joint is a tripod joint. The tripod joint may include a spider, commonly referred to as a tripod, which typically includes three trunnions. The spider may be received by an outer joint portion, which is also called a tulip. The tulip includes an inner recess with three vaults, where the vaults are connected to each other by a tulip minor surface. Each of the three vaults receives one of the trunnions of the spider. The tulip may include an outer profile that substantially coincides with the overall shape of the spider. That is, the outer profile of the tulip is non-circular, and includes a profile that corresponds with the three vaults of the spider. The part of the outer profile that corresponds with the three vaults is called the vault portion and the part of the outer profile that corresponds with the minor surface is called the tulip minor surface portion.
An insert may be placed over the tulip. The insert includes an aperture that receives the tulip and substantially coincides with the non-circular outer surface of the tulip. The aperture includes an inner sealing surface. The part of the inner sealing surface that seals along the tulip minor surface portion is called the root portion, and the part of the inner sealing surface that seals along the vault portion is called the track portion. A sealing boot may then be inserted over the adapter and a clamp may then be placed over the sealing boot and the adapter. The clamp compresses the boot and insert against the tulip.
The insert may also include a sealing bead that is located at the inner sealing surface. When the adapter is clamped against the tulip, the bead deforms against the outer profile of the tulip, forming a seal between the adapter and the tulip. The seal formed by the bead is for reducing the amount of grease that is located inside the joint from escaping into the environment. The bead may also reduces the amount of contaminates, such as dirt and water, from entering into the joint. However, in some instances, the sealing bead of the adapter does not always contact and seal along the outer profile of the tulip. This sealing issue is present along the entire outer profile of the inner sealing surface, but is sometimes especially prevalent at the root portion of the inner sealing surface. The adapter may not contact the tulip at the root positions of the adapter especially if the adapter is constructed from a flexible, rubber-based material. This is because the root portion is located the furthest distance away from the clamp than any other portion of the inner sealing surface, and receives the least amount of pressure from the clamp. Also, the geometry of the inner sealing surface at the root does not allow for optimal sealing between the tulip and the inner sealing surface.
Therefore, there exists a need to provide an adapter for sealing the tulip of a joint assembly that includes an improved sealing feature located along the root portion of the adapter.